The present invention concerns the processing of semiconductor wafers and pertains particularly to determining the source of contamination introduced during wafer processing.
During the course or processing semiconductor wafers, processing fluids, such as ultrapure water, are used for a variety of purposes, including cleaning the wafers. In order to produce processing fluid without contaminants, sophisticated processing fluid production systems are used. These processing fluid production systems virtually eliminate contaminants from water.
Occasionally within the processing fluid production system or within the distribution system of the processing fluid, impurities can be introduced. Contaminants, even at a concentration of one part per trillion, can have a negative impact on wafer processing. When contaminants are introduced into a processing fluid production and transportation system it is necessary to locate the source of contamination and correct the contamination problem.
One method of detection of contamination is to sample the processing fluid at various locations within the processing fluid production and transportation system. The sampled fluid can be analyzed to determine contaminant concentrations. However, existing methods to directly measure fluid for contamination concentration are generally not sensitive enough to reliably detect the part per trillion levels of contaminants which are sufficient to disrupt the processing of wafers. It is desirable therefore to discover a better way to detect contaminant concentrations within a processing fluid production and transportation system.